FindLAPACK: Test for implicitly linked LAPACK libraries

Apply the change from commit 5b8f69ebe9 (FindBLAS: Detect implicitly
linked BLAS library, 2018-08-28, v3.13.0-rc1~150^2~2), to FindLAPACK
also.  Typically both BLAS and LAPACK are provided the same way,
e.g. in a Cray Compiler Environment.
1 file changed